#ifndef _MEMDC_H_
#define _MEMDC_H_

//////////////////////////////////////////////////
// CMemDC - memory DC
//
// Author: Keith Rule
// Email:  keithr@europa.com
// Copyright 1996-2002, Keith Rule
//
// You may freely use or modify this code provided this
// Copyright is included in all derived versions.
//
// History - 10/3/97 Fixed scrolling bug.
//                   Added print support. - KR
//
//           11/3/99 Fixed most common complaint. Added
//                   background color fill. - KR
//
//           11/3/99 Added support for mapping modes other than
//                   MM_TEXT as suggested by Lee Sang Hun. - KR
//
//           02/11/02 Added support for CScrollView as supplied
//                    by Gary Kirkham. - KR
//
// This class implements a memory Device Context which allows
// flicker free drawing.
//
//
// I made a few changes to support transparency effect 
//
// Line 44 : Added bBg parameter.
// Line 83 ~ 87 : If bBg is TRUE, copy background.
//
namespace BitmapSlider
{
	class CMemDC : public CDC {
	private:	
		CBitmap		m_bitmap;		// Offscreen bitmap
		CBitmap*	m_oldBitmap;	// bitmap originally found in CMemDC
		CDC*		m_pDC;			// Saves CDC passed in constructor
		CRect		m_rect;			// Rectangle of drawing area.
		BOOL		m_bMemDC;		// TRUE if CDC really is a Memory DC.
	public:

		CMemDC(CDC* pDC, const CRect* pRect = NULL, BOOL bBg = FALSE) : CDC()
		{
			ASSERT(pDC != NULL); 

			// Some initialization
			m_pDC = pDC;
			m_oldBitmap = NULL;
			m_bMemDC = !pDC->IsPrinting();

			// Get the rectangle to draw
			if (pRect == NULL) {
				pDC->GetClipBox(&m_rect);
			} else {
				m_rect = *pRect;
			}

			if (m_bMemDC) {
				// Create a Memory DC
				CreateCompatibleDC(pDC);
				pDC->LPtoDP(&m_rect);

				m_bitmap.CreateCompatibleBitmap(pDC, m_rect.Width(), m_rect.Height());
				m_oldBitmap = SelectObject(&m_bitmap);

#ifndef _WIN32_WCE
				SetMapMode(pDC->GetMapMode());

				SetWindowExt(pDC->GetWindowExt());
				SetViewportExt(pDC->GetViewportExt());
#endif
				pDC->DPtoLP(&m_rect);
#ifndef _WIN32_WCE
				SetWindowOrg(m_rect.left, m_rect.top);
#endif
			} else {
				// Make a copy of the relevent parts of the current DC for printing
				m_bPrinting = pDC->m_bPrinting;
				m_hDC       = pDC->m_hDC;
				m_hAttribDC = pDC->m_hAttribDC;
			}

			// Fill background 
			if( bBg )
				BitBlt(m_rect.left, m_rect.top, m_rect.Width(), m_rect.Height(),
				m_pDC, m_rect.left, m_rect.top, SRCCOPY);
			else
				FillSolidRect(m_rect, pDC->GetBkColor());
		}

		~CMemDC()	
		{		
			if (m_bMemDC) {
				// Copy the offscreen bitmap onto the screen.
				m_pDC->BitBlt(m_rect.left, m_rect.top, m_rect.Width(), m_rect.Height(),
					this, m_rect.left, m_rect.top, SRCCOPY);			

				//Swap back the original bitmap.
				SelectObject(m_oldBitmap);		
			} else {
				// All we need to do is replace the DC with an illegal value,
				// this keeps us from accidently deleting the handles associated with
				// the CDC that was passed to the constructor.			
				m_hDC = m_hAttribDC = NULL;
			}	
		}

		// Allow usage as a pointer	
		CMemDC* operator->() 
		{
			return this;
		}	

		// Allow usage as a pointer	
		operator CMemDC*() 
		{
			return this;
		}
	};
}

#endif